1,720,973 research outputs found
Micromotions measurement to assess hip stem mechanical stability: an intra-operative device
No full textSubject -specific FE model for the prediction of the relative micromotion in a total hip implant: verification and validation
No full textThe most common reason for the aseptic loosening of
cementless hip stem is the lack of primary stability as the
presence of an excessive relative micromotion at the boneimplant
interface [1]. Despite pre-clinical validation has
remarkably improved over the last few years, some important
factors affecting implant biomechanics have still to be
considered. Most of the previous numerical studies on hip
arthroplasty were based on models of composite femurs.
However, subject-specific factors (skeletal anatomy,
mechanical properties, implant position) are needed to
produce helpful outcomes for clinical practice. In addition,
these models were developed using time consuming structured
meshes frequently lacking of careful verification and
validation phases.
Aim of the present work is the development of a Finite
Element (FE) model of an implanted femur taking into
account the specificity of subject as well as the planned
surgery technique parameters.
Specific aims are the verification of the numerical accuracy of
the FE model and the analysis of the predicted relative
micromotions compared to experimental results (validation)
Predicting the subject-specific primary stability of cementless implants during pre-operative planning: preliminary validation of subject-specific finite-element models
No full textPre-operative planning help the surgeon in taking the proper clinical decision. The ultimate goal of this work is to develop numerical
models that allow the surgeon to estimate the primary stability during the pre-operative planning session. The present study was aimed to
validate finite-element (FE) models accounting for patient and prosthetic size and position as planned by the surgeon. For this purpose,
the FE model of a cadaveric femur was generated starting from the CT scan and the anatomical position of a cementless stem derived by
a skilled surgeon using a pre-operative CT-based planning simulation software. In-vitro experimental measurements were used as
benchmark problem to validate the bone–implant relative micromotions predicted by the patient-specific FE model. A maximum torque
in internal rotation of 11.4Nm was applied to the proximal part of the hip stem. The error on the maximum predicted micromotion was
12% of the peak micromotion measured experimentally. The average error over the entire range of applied torques was only 7% of peak
measurement. Hence, the present study confirms that it is possible to accurately predict the level of primary stability achieved for
cementless stems using numerical models that account for patient specificity and surgical variability.
r 2006 Elsevier Ltd. All rights reserved
La riqualificazione delle attività estrattive dismesse nella Valle del Rio della Rocca (Re): un progetto tra fruizione e conservazione
No full textThe aim of this project is to deal with the issue of the requalification of abandoned extractive areas, through the case study of Rio della Rocca Valley in Castellarano (Reggio Emilia), which has been a Site of Community Importance since 1995. What is peculiar to these areas is the coexistence of several significant aspects such as industrial history, flora and fauna of a region; consequently, quarry areas represent much more than empty spaces in the landscape. There is the urgent need to renovate and requalify the area we are taking into examination, which is nowadays, as the mining activities ceased, in a general state of disrepair. Our purpose is to plan a system that allows the coexistence of the previously mentioned aspects with recreational fruition, in order to revitalize the area. Thanks to this system, the quarries will no longer be cut off on the borders of the valley, but they will be naturally linked to the nearby areas. Hence, some paths and elements of the area, as for instance the artifacts of industrial archeology, will continue to be proper attractions for visitors who are aware of the value of preservatio
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The effect of composition on structural, thermal, redox and bioactive properties of Ce-containing glasses
Full text linkThe effect of phosphate on the ability of Ce-containing bioactive glasses to inhibit oxidative stress was studied on compositions based on Hench (46.2%SiO224.3%Na2O26.9ÊO2.6P2O5, mol%) and Kokubo (50.0%SiO225.0%Na2O25.0ÊO) glasses. In particular, the reduction of catalase mimetic activity of Ce-containing glasses due to the presence: i) of P2O5 in the glass compositions, and ii) of phosphate groups in the solution employed for catalase mimetic activity tests was explained and rationalized by combining SEM, XPS, XRD, DTA, FT-IR and UV-vis experiments with Molecular Dynamics simulations.The results suggest that the Ce ions play a different structural role in the two series of glasses. In particular, in phosphate free glasses Ce is coordinated by non-bridging oxygens (NBOs) originated from the disruption of the silicate network, whereas in phosphate containing glasses the NBOs around Ce ions belong to orthophosphate groups. The latter groups stabilize the Ce3+ species subtracting them from the interconversion process between Ce3+ and Ce4+, which is of fundamental importance for the exhibition of the catalase mimetic activity
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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